Sanford Police Chief Bill Lee is temporarily stepping down amid accusations that his department bungled the investigation into the shooting death of Florida teen Trayvon Martin.

Lee's announcement he was stepping aside came shortly before Florida Gov. Rick Scott said another key investigator tied to the case, State Attorney Norman Wolfinger, also had agreed to withdraw. Angela B. Corey of the 4th Judicial Circuit Court was appointed to replace Wolfinger.

Scott added that Lt. Gov. Jennifer Carroll would lead a special new task force to prevent future tragedies like Martin's death that would "conduct public hearings, take testimony and recommend actions -- legislative and otherwise -- to both protect our citizens and safeguard our rights."

Lee, in a hastily organized press conference, said he was stepping down because he "hopes to restore semblance of calm to the city." He added, "My hope is that the investigation process will move forth swiftly."

Lee said he stands by his department's investigation and the officers involved, but he acknowledges that he has become "a distraction from the investigation."

"It is apparent that my involvement in this matter is overshadowing the process," he said.

City Manager Norton Bonaparte, who had earlier said he would defer any decision on Lee's fate until after a thorough investigation had been completed, said, "What the city of Sanford wants more than anything else for the family of Trayvon Martin is justice."

"We are looking for a complete, thorough review," he said. "Justice will prevail."

Martin, a 17-year-old black youth, was carrying only a bag of Skittles, iced tea and his cell phone, when Zimmerman allegedly killed him on Feb. 26.

While Martin's family has repeatedly called for Zimmerman's arrest, Sanford police accepted Zimmerman's claim that the shooting was in self defense.

Lee's resignation comes as the Sanford police department has come under increased scrutiny for an investigation that some say they botched from the very start.

The list of possible police missteps uncovered by ABC News is long: The department allegedly ignored some witnesses while failing to follow up with others. One officer "corrected" the testimony of an eye witness who said she heard "the boy," Martin, crying out; the officer allegedly told the witness that it was Zimmerman who was screaming for help.

Most egregious, say experts, was the failure of the department to follow up with Martin's girlfriend, who was on the phone with him in the seconds before Zimmerman confronted Martin and shot him dead. Police had Martin's cellphone call logs but never reached out to the girl, who said that Zimmerman followed, pursued and accosted Martin.

"That's a serious, serious fatal flaw," said Rod Wheeler, a homicide investigator who is not involved with the case, "and it could be a fatal flaw in this investigation. And the police department definitely needs to go back, re-interview anyone and everyone that has any information."

Wheeler said that investigators from the justice department will also begin their investigation with new witness interviews. On Monday, it was announced the FBI, the Justice Department's Civil Rights Division, and the U.S. Attorney's Office for the Middle District of Florida will investigate the killing.

And while law enforcement analysts tell ABC News that Zimmerman sounded intoxicated in his call to police that night, police never gave him a toxicology test, which is standard in most homicide cases. Police also did not check Zimmerman's vehicle or impound it.

The FBI has said it is now examining the 911 tapes, which include a possible racial slur believed to be muttered by Zimmerman, a neighborhood crime watch volunteer who pursued Martin, confronted him and after a scuffle shot him dead.

The Martin family also criticized the Sanford police department for failing to identify their son more quickly. Martin's body was left in the morgue for three days, classified as a "John Doe." The family charges that officers didn't bother to ask neighbors if they recognized Martin, who had been staying with his father in the neighborhood.